If asked where they expect the biggest technological innovation of the 21st century, most people would probably answer either in genetical engineering or in AI/robotics. And these people may be right, although I personally doubt the latter (AI is vastly overhyped at the moment).

Myself, I would go out on a limb and say it’s optical computing. This may seem like an odd choice, but let me explain. Our current electronic computers are pretty good, but they have some severe limitations: They use a lot of electricity and get very hot in use (hence the ridiculous fans on modern CPUs/GPUs). As the speed of these conventional computers increases, so does their use of electricity and the production of heat. Engineers counter this by shrinking the electronical components (e.g. the structures of microprocessors), but there are some natural limits as to how far these can be shrunk. It looks increasingly like the performance increases we have seen in conventional electronic computers in the past decades won’t go much further. It may therefore become necessary to make a leap to a different technology to increase the computing power.

Optical computers use light (photons) instead of electrons to transport signals. The technology is not new, and optical elements are already in use in some areas of computing today, for example in fiber cable networking. The speed of optical computing is far superior to electronic computing – it is (roughly speaking) computing at the speed of light. It also uses far less energy and produces less heat.

Apparently there are still major hurdles that prevent us from making full fledged optical computers, none of which I understand as a layman. According to what I read, it is hard to build a purely optical transitor. I have also read that it is a problem that photons are much bigger than electrons, and it is difficult to handle them in miniaturized components as is done with electronic computers. But let’s dream a little. If an optical transistor could be built, and if the remaining problems with optical computing could be solved in the coming decades, we could suddenly have computers at our fingertips which are an order of magnitude faster than the ones we currently have. This has the potential to change the world of science and technology drastically.

For example, imagine a smartphone based on optical computing. It would not only be massively faster, but would also use much less power than current smartphones and therefore last much longer with one battery charge.

Of course it would not all be good news. If they become reality, optical computers would also make even greater computer surveillance possible and pose challenges for security (e.g. by allowing the brute-forcing of passwords in much less time). But any new technology comes with the potential for abuse.